This invention relates to carburetors for internal combustion engines and more particularly to air-valve type carburetors for internal combustion engines that are utilized to propel vehicles such as automobiles.
Most present day automobile carburetors are designed with a venturi to create a vacuum pressure in the emission chamber to pull fuel from a fuel reservoir. The venturi, by its fixed nature, operates at maximum efficiency over a small range of engine speeds. Furthermore a different size venturi is generally required for different size engines. Seldom is the automobile operated in only a small range of speeds. Consequently, various complicated venturi arrangements including multiple venturi tubes have been included in carburetors in an attempt to make the carburetor more efficient over a wide range of operating conditions. A venturi is generally most ineffective at slow speeds in which the velocity through the venturi is minimal. Consequently, special idle jets have been incorporated in carburetors to pass additional fuel to the engine at low speeds. At higher speeds, the fuel from the special jet is not required and provides a richer mixture then is needed. Such a loss is particularly noted at high speeds during deceleration.
Over the years additional features have been added to carburetors to overcome certain limitations in a fixed venturi carburetor. One limitation is presented when the carburetor is moving at a slow speed and the driver desires to quickly accelerate the automobile to pass another vehicle. Quick depression of the throttle pedal, causes the throttle valve to rapidly open. This causes additional amounts of air to flow through the venturi without substantially increasing the vacuum pressure to draw additional fuel. Consequently it is not infrequent that the engine would stall on the lean mixture. To overcome such a limitation, accelerator fuel pumps have been incorporated in carburetors to pump additional fuel into the mixing chamber when the throttle is depressed rather rapidly. However, such a compromise results in the loss of fuel when the vehicle is traveling at high speeds and the accelerator pump is temporarily released and then depressed again. The pump adds the additional fuel to the engine which is wasted since the high air velocity through the venturi is sufficient to pull enough fuel into the cylinders to accomplish the objective without the necessity of the fuel pump. Consequently, an additional feature to overcome one limitation frequency causes additional inefficiencies over other operating conditions.
Another limitation is encountered when the vehicle is traveling at an intermediate speed with the throttle almost fully depressed. This condition occurs when the automobile is climbing a hill or encounters a heavy headwind. Under such conditions, the velocity in the venturi is insufficient to pull the fuel. To compensate for this problem, many carburetors utilize metering rods to delivery more fuel to the venturi. All of these additional features are attempting to compensate for the inefficiencies of the venturi over the full range of operating conditions. Ideally, the carburetor for an automobile should operate at high efficiencies over a full range of engine operating conditions.
Conventional air-valve type carburetors have been utilized in which the system attempts to maintain a constant air velocity across a jet fuel orifice independently of the throttle valve position and engine speed. Such carburetors generally attempt to vary the size of the fuel jet in accordance with the amount of air entering the carburetor to provide a correct "air-fuel ratio". However engines having such air valve carburetors are generally difficult to start and operate at idling speeds. Plus special fuel metering circuits are generally required to provide a richer mixture when quick acceleration is required.
Each additional feature added to the carburetor makes it more complicated and more susceptible to plugging necessitating frequent maintenance and adjustment. The number of moving parts in carburetors has increased substantially over the years making the carburetors extremely complicated and more expensive to manufacture.
One of the noted problems of prior art venturi and air valve carburetors in addition to the foregoing is the inability to efficiently and effectively vaporize and mix the fuel with the air prior to discharge into the intake manifold of the engine over the full range of operating conditions.
One of the principal objects of this invention is to provide a very simple carburetor of the air-valve type in which the fuel is efficiently and effectively mixed with the air prior to discharge into the intake manifold to increase the efficiency of the combustion in the combustion chamber.
An additional object of this invention is to provide a very simple carburetor with no moving parts in the fuel metering system in which the fuel air ratio may be varied over the full range of the engine in operating conditions.
A further object of this invention is to provide a very simple air valve carburetor in which all of the fuel is added through a single fuel circuit over the full range of the operating conditions of the engine.
An additional object of this invention is to provide an air type valve carburetor that may be utilized with minimum adjustments for various size engines.
A further object of this invention is to provide an air valve type carburetor that does not have an idle jet, an accelerator pump or a needle valve or jet.
An additional object of this invention is to provide a carburetor not having a venturi or a variable size fuel nozzle.
A further object of this invention is to provide an air valve type carburetor in which the amount of fuel may be varied without having to increase or decrease the size of the fuel jets or nozzles in the mixing chamber.
A further object of this invention is to provide an air valve type carburetor in which the fuel is uniformly discharged into the air at multiple locations and is effectively mixed prior to discharge into the intake manifold.
An additional object of this invention is to provide a carburetor of the air valve type that is capable of automatically adjusting to different atmospheric pressures to enable the engine to adjust to various altitudes.
A still further object of this invention is to provide a carburetor that is extremely simple to manufacture and very easy to maintain.
These and other objects and advantages of this invention will become apparent upon reading of the following detailed description of a preferred embodiment.